In 1835 Landsberg was engaged as teacher at the Nauensche Institute for the education of boys, and from 1839 to 1846 he was its director, in which position David Cassel was his successor. From 1838 to 1846 he preached regularly at the bet ha-midrash and at the synagogue of Commerzienrath Lieberman.In 1846 he was appointed "Landrabbiner" of Hildesheim, which position he filled until his death. Although himself very strict in the observance of the ceremonial law, he was of a progressive spirit. In the synagogue built during his administration (1849) an organ was introduced, a mixed choir established, some German prayers introduced, and the "piyyutim" nearly all abolished. Confirmations of boys and girls were held every year.